This invention relates to an embolic protection filter, which is movable between a collapsed configuration for transport through a vasculature and an expanded configuration for deployment in a vasculature.
It is known to collapse down and load an embolic protection filter into a delivery catheter. The collapsed filter may then be transported through a vasculature using the delivery catheter until the filter is located at a desired site in the vasculature where the filter may be deployed out of the delivery catheter.
It is also known to coat embolic protection filters with a biocompatible coating to minimize the risk of fibrin build-up on the filter, and the risk of clots forming in the blood stream.
Many of these biocompatible coatings have hydrophilic properties. These hydrophilic coatings interact with water molecules. Water molecules may be absorbed during manufacture, sterilization, storage or in use. Often the quantity of water absorbed is low leading to the biocompatible coating swelling slightly, and the coating becoming sticky or tacky.
Filter membranes in this state have the potential for self-adherence and this can lead to the collapsed filter becoming stuck to itself in the collapsed configuration with the result that the filter will fail to expand fully, or even expand at all, when deployed in the vasculature. Failure of an embolic protection filter to correctly deploy in a vasculature can potentially lead to embolic material migrating downstream through the vascular system with potentially life-threatening consequences.
Another problem which arises with a low profile filter loaded into a catheter pod is the difficulty in successfully flushing the device to remove any air. Because the filter assumes a packed configuration in the pod it is difficult to remove air from the filter. It may also be easier for the filter to remove itself from the pod due to the flushing pressure in preference to the filter being flushed of air.
This invention is therefore aimed at overcoming at least some of the problems associated with known embolic protection systems.